Have a look at Surly Straggler or Midnight Special. These are stout steel bikes that would handle everything you are talking about. Also look at the the sister brand of Surly All City bikes, they have at least five that would work well. The Space Horse GRX is just one I would look at but there are others.
Personally I wouldn't recommend touring bikes, tire clearance can be an issue if you truly want a gravel bike.
The other route you could go is touring without a rack. Bag manufactures have come a long way of fitting bags to bikes for the gravel adventure series. So many to choose from. Good luck in your search.